Sawmill dog



March `1, 1932. R LANGILL ET AL SAWMILL DOG original Filed April 28.192'7 3 Sheets-Sheet 2 INVENTOR.

mi M 46V )umu-f ATTORNEY5.

March 1, 1932. R. LANGILL ET AL SAWMILL DOG f Original Filed April 28.1927 3 Sheets-Sheet 3 www Wm MMM@ L m 4 Patented Mar. l, 1932 nNTEDSTATES 4PAralar OFFICE ROSS LAN GILL AND STANLEY B. LANG-ILL, MENOMINEE,MICHIGAN, ASSIGNORS T0 THE PRESCOTT COMPANY, OF MENOMINEE, MICHIGAN, ACORPORA'J?IONV OF MICHI- GAN SAWMILL Doe s Application `filed April 28,1927, Serial No. 187,170 `Renewed January 9, 1931.

This invention relates in general to saw.

mill dogs, and more particularly to an im'- proved fluid pressureoperated sawmill' dog of the type forming the subject matter of theeo-pending application of Adolph L. Haase, for sawmill dog, filed June(i, 1925, Serial No. eased l The object of the invention is to providean improved type of sawmill dog of this character wherein a fluidpressure'motor operates through a chain or other similar flexible ele-vment for the purpose not only of positively and powerfully urging bothlog engaging members into proper gripping engagement with the log orboard, but also for positively retracting both of the log engagingmembers. In other words, both'log ei'igaging members are positivelyforced into gripping engage ment with the log or board, 'and both logengaging members are positively forced apart to disengage the log orboard.

Another important object of the invention is to provide a'sawmill dog ofthis character 'which is' organized With'the knee 1n such H manner thatthe entire dog may shift back and forth with respect to the vface of theknee under the control of a liuid pressure motor whereby the logengaging members maybe positioned well out beyond the' face of the kneefor the purpose ofengaging a log or heavy timber, and also may bepositioned adjacent the face of the knee for the purpose of 'engaging aboard of relatively th'inor'light timber. n

Another object is to'provide adeg of this character 'wherein vtheflexible element is'so organized 'with the fluid pressure motor, theframe of the dog and the log engaging mem` bers as to impart a straightline movement to the log engaging'members in such manner as not to tendto bind the same.

A further object is to provide a dog having the advantages andcapacities referred to and which is of simple and durable construction,reliable and effective in operation, easily controllable, 'andcomparatively inenpensive to manufacture.

Other objects and advantages reside in certain novel features of the,construction, arrangement aud combination o fparts which will behereinafter more fully described and' vention and organized AWith a kneeplate whereby it is attached Yto the knee of the sawmill; and

Figure 2 is a View partly in side elevation looking toward .the oppositeside ofthe air dog from that shown in Figure l and partly in verticalsection, the dog being shown 'mounted on the knee of the sawmill; and

F igureB isa view 1n front elevation of the arrangement shown 1n Figure2; and.

Figures 4 and 5 are views in horizontal sec- -tiontaken on line t`4ofFigure 3, but showing the different positions of the dog relative to theface of theknee; and

Figure 46 is a fragmentary View in side elevation similarto Figure l butillustrating a different position of the dog relative to the knee face;and y 4'Figure 7 isafragmentary view in section von line (1-7 of Figure6. Y v

- `Referring,to the drawings, it will be seen that thedog embodying thepresent invention includes a frame designated generally at l, the frame1 having'a horizontalbase portion 2, a vertical side` portion 3 vwhichmay be ribbed-`for ,strength and cut out to reduce :its weight, and ahorizontal top portion 4.

Preferably, the frame is a one piece casting, the ibase port1on2 and-topportion 4L of the frame l fhavmg' aligned sockets 5 formed thereon, andin these aligned sockets the ends of a pair of front guiderods 6 and ofa single rear guide rod 7 are lit-ted and secured as by means ofpins 8.

Gnltlie front guide rods 6 an upper logr engagmgniember designatedgenerally at 9 and a lower log engaging member designa-ted generally at10` are mounted for vertical slidving `movement toward and awayy fromeach other. The log engagingzmemberst) and 10 comprise slides 1l and l2respectively, the slides ll and 12 having openings in which therods 6are slidably fittedwhereby the a piston 23,

slides 11 and 12 may be freely adjusted up and down on the rods 6. Adownwardly directed log engaging tooth 13 is fixed to and carried by theslide 11 and a similar but upwardly directed tooth 14 is fixed to andcarried by an integral extension 12a of the slide 12. v

For the purpose of positively pulling the log engaging members towardeach other and into engagement with the log,or the like, and also forpositively pulling both of the log engaging members out of the log andaway from each other a fluid pressure motor designated generally at F ismounted on the frame and is operatively connected to the `log engagingmembers in a manner which will be hereinafter more fully described.

rlhe'iiuid` pressuremotor F comprises a ,movable cylinder 15 havingintegral apertured guideV lugs 16 which slidably receive the guide rod7whereby the 'cylinder 15 is .constrained to slide up and down on theguide rod 7 .closed by heads orl end members 17 equipped with stuiingboxes 18 through which the At its ends the cylinder 15 is upper andlower sections 19 and 2O of a pis- AVton rod designated generally at 22are slidably eat-ended. As shown in Figure 2, the adjacent ends of thesections 19 and 2O of the piston rod 22 are threadedly connected withthe piston 23 being a working fit in the cylinder 15. The lower end ofthe lower section of the piston rod 22 is fastened'in any suitablemanner to the base portion v2 of the frame, a nut 24 being shown forthis purpose inFigure 2. The upper section 19 of the piston rod 22 issimilarly fastened to the top portion of the frame, and, in

the embodiment of the invention illustrated, a cap 25 is threadedlyengaged with the upper section-19 of the piston rod and bears againstthe top portion of the frame toobtain the Yfastening action.

It will now be understood that with this assembly `of the movablecylinder 1,5 and the stationary piston 23 the lcylinder will be moveddownwardly when pressure is supplied vbelow the piston` 23 and permittedto exhaust from above the piston 23, anden the other hand, the cylinder15 will be moved upwardly when the pressure is supplied above the piston23 and permitted to exhaust from below the piston 23.

lnA order to conveniently supply and exhaust the pressure above andbelow .the piston in the manner required for proper operation, the uppersection 19 of the piston rod 22 is made up of' concentric tubes 26 and27 the tube 26 being threaded into the piston 23 and having-ports 28which communicate with the interior of the cylinder 15 above the piston23. The upper end of this tube 26 is threaded into the cap 25 andcommunicates with a chamber 29 therein. The tube 27 is threaded into anaxial passage 30 provided in the upper end and ofthe section 2O of thepiston rod 22 and communicating at its lower end with a diametricalpassage 31 which opens out into the interior of the cylinder 15 belowthe piston 23. The piston 23 is, of' course, formed with an axialopening into which the sections of the piston rod are threaded. Theupper end of this inner tube 27 is suitably connected to the cap 25 andcommunicates with a chamber 32 formed in the cap 25 and entirelyseparated from and non-communicable with the chamber 29 of the cap. Apipe 33 which leads from any suitable source of supply of fluid pressureconnects with the valve casing 34 of a conventional four-way valve 35.rl`he casing 34 has a vent 36 leading to the atmosphere and also has asuitably ported plug 37 which controls communication of the pressuresupply pipe 33 and venty 36 with pipe lines 38 and 39 leading to thechambers 29 and 32 respectively.

By turnin T the valve to one position the fluid pressure supply pipe 33is placed in communication with the pipe 39 and the pipe 38 is placed incommunication with thevent 36, thereby 'causing fluid pressure to flowinto the chamber 32, down through the tube 27 to the passage 30 andthence through the passage 31 into the cylinder 15 below the piston 23.This forces the cylinder 15 downwardly and the air in the cylinder 15above. ythe piston 23 escapes through the ports 28,

tion of the valve, pressure is trapped on both sides of the piston andthe cylinder is locked in position. p

rf'he downward Vmovement of the cylinder 15 is utilized to pull the logengaging meinbers together to cause them to powerfully and properly gripthe log or the like, and in carrying out this purpose the lower lend ofthe cylinder l5 is provided with a pair of lugs 4() which-may be castintegral with the cylinder at one side of the center thereof. On theselugs 40, a sprocket wheel 41 is rotatably' mounted and meshes with anintermediatel portion of a sprocket chain 42.A The sprocket chain 42 hasone end connected as at 43 with the upper rearward portion of the slide11 of the logengaging member 9. This chain 42 is then extendeddownwardly to the sprocket s wheel 41 and after passing under and aroundthe sprocket wheel 41 is extended upwardly to a sprocket wheel 44rotatably mounted on a resiliently supported hanger bracket 45.

The bracket V45 has a stud 46 fixed theretoV and this stud passesthrough an opening in the top portion 4 of the frame and is yieldablysupported on the frame against downward movement by means ofthevcompression coil spring 47 encircling stud 46 above the frame andhaving its lower end engaging' the top of the 'frame and its upper' endenga gingan adj ustable abutment on the stud 46, which abutment mayconsist of a washer 48 and nuts 49. After passing over and around thesprocket wheel 44 the chain 42 extends downwardly between the guide rods6 and passes through an opening 11 provided in the slide 11 (see Figs. 4and 5) and on down to the slideY 12 ofthe log engaging member 10, thechain 42 being fixed to the slide 12 as indicated at 50 (see Fig. v3).The chain 42 connects with the top of slide 12 near its center and thusexerts an even and direct pull on the slide which moves the same withouttending to bind iton its rod 6. The

saine effect is approximated inrespect of the connection .of the chain42 to the slide 11. )Vith this arrangement, when the cylinder15 movesdownwardly the sprocket wheel y 41 acts on the chain 42 to cause thechain to pull the log engaging member'9 downwardly and the logengagingmember 12 upwardly, thus causing the teeth and 14 of the logengagiii members to engage and bite into the log, as illustrated indotted lines in Figure 2.

The spring 47 and bracket 45 and associated parts provide a tensioningdevice and shock absorber which takes up slack in' the chain 42, andalso relieves the other elements of the dog of severe shocks andstrains.

The upward movement of the cylinder 15 is .utilized to positively pullboth log engaging members out of the log and away from each other, and.for effecting this operation, a sprocket wheel 51 is rotatably mountedon lugs 52 cast integral with the upper end of the cylinder 15 on theopposite side ofthe center from the lugs (see Fig. 3). A sprocket chain53 is fixed as at 54 tothe lower rearward portion of the slidefll of thelog engaging member 9 and -is then passed up and over the sprocketwheel51 and down to, around and under a sprocket. wheel 55 rotatablymounted on a bracket 56 fastened to` the base portion 2 of the frame 1.p After passing under and around the sprocket wheel 55 the chain 53 isfixed as at57 to the upper rear@ ward portion of the slide 12 of the logengaging member 10. When the cylinder 15 moves upwardly, the sprocketwheel 51 acts -onthe chain 53 to cause it to move the log engagingmember 9 upwardly and the logengaging member 10 downwardly, a positivepull being exerted on both log engaging members for disengaging themfrom the logand moving them apart. However, when the cylinder'l is moveddownwardly and the' log engaging lmembers 9 andL 10 move toward eachother by the action of the chain 42, then the. chain 53 is slackened inproportionto permit the chain 42 to bring the log engaging memberstoward each other.

In the drawings (see Figs. 2, 4 and 5) the centers of the sprocketwheels 41 rand 51 are shown slightly oset from each other in a directiontransversely ofthe vsawmill carriage, and ywhile this may be done it hasbeen soshown merely to facilitate illustration and understanding of thearrangement of the chains 42 and 53. In building a dog the axes of thesprocket'wheels 41 and 51 will lie in the sameA vertical plane although-these sprocket wheelsv willbe oifsetslightly in this plane in thedirection of. the length of the sawmill carriage.

` To enable the dog to engage either a-heavy ,log ortimbei' or arelatively light board -to best advantage it is proposed to mount thedog upon the knee in such a manner that it can be shifted in and outrelative to the knee face.v In carrying'out this purpose a knee plate 60is provided and-is rigidly and securely fastened tothe knee61 bysuitable fas- -tening devices.` The fa ce of the knee is designated at62. (')n this knee plate the frame 1 of the dog is'mounted for in andout movenient, this mounting being effected by means of headed studs 63extending through slots 64 in the kneel plate 60 and threaded into theYframe 1. Antifriction sleeves or collars 63a are provided on the Shanksof the studsf63 andengage the walls of the slots 64. This shiftablemounting of the vframe of the dog of the knee plate is also aided by themechyanism employed for eifectingand controlling the in and outmovement, as will hereinafter more fully appear.A

The mechanism for shifting frame 1 in and out comprises a power cylindersuitably fixed to the frame 1 and having a piston A71'1itted therein forsliding movement. Piston 71 has piston rod 72 which projects beyondboth-ends of the cylinder, the rod 72 extending through stufling boxes73 on the endplates of the cylinderTO. Theupper and lower portions ofthe piston rod 72 are formed with racks 74 which are slidablymounted inguides `75 on the frame 1 and which mesh with mutilated pinions 78having bearing portions 79 journalled or rotatably mounted in bearingsY8O provided therefor in the frame 1 (see Figures 2,4 and 5). Eachbearaing portion 7 9`of each pinion 7 8 has a disk 81 pnned or otherwisesuitably fixed thereto. The discs 81 operate in elongated bearing lopenings or slots 82 provided therefor in the knee plate 60 and thesediscs 81 have flanges 133 coacting with the frame 1 to hold the discsin; the slots 32 and yet leave them free to roll back and forth in theseslots. Each disc 81 has Van eccentric pin or crank pin 84 threadedtherein or otherwise suitably fixed thereto, each pin 84 being pivotallyconnected to one end of a link 85, the other end of theliiik S5 beingpivotally mounted on a pin or stud 86 threaded into or otherwisesuitably fixed to the knee plate 60. Pressure is supplied. to either endof the cylinder 70 and exhausted from the opposite end thereof of the`control of the conventional four way may be projected.

i nfl vvalve Si' having ports communicating with source of supply otfluid pressure and with the atmosphere, and also connected with the pipeSSVleading to the opposite ends of the cylinder 0. s

Figure 1 shows' the dog positioned with the log` engaging membersretracted or positioned as far inwardly as they may be with respect tothe knee face; To project the dog and its log' engaging members, fluidunder pressure is suppliedto the upper end of thecylinder 70 exhaustedfrom the lower end thereof. This moves the piston 71 downwardly andconsequently moves the rack 74: downwardly, thereby'rotating themutilated pinion 78 and consequentlyv the discs 81. As the Ydiscs S1have their crank pins pivoted tothe links 85, which are constrained toswing about allred axis, the discs 81, when rotated, roll along.theslots 82, and when they are rotated by downward movement of the rack74, they roll from the position shown in Figure 1 to the position shownin Figure, thereby moving the dog forwardly with respect to the kneeface to project the log engaging members outwardly beyond the knee faceas far as they Reverse movement of the piston 71 causes reverseoperation of these parts and shifts the .dog rearwardly on the -kneeplate to lmove the log engaging members from the full line position ofFigure 6 and the dotted line position of Figures 1 and 2 to the i'ullline positions of Figures 1 and 2.

As clearly shown in Figures 1 and 6, the elongated slots or bearingopenings 82 are formed with enlargement 82. at their ends. This preventsthe discs 81 from striking the ends ofthe slots7 the discs merelyrolling along the guide portions 82h of the slots.

'lVhen the frame 1 and the mechanism carried thereby has been shifted toeither of its extreme positions the links 85 are on dead center as willbe understood from a comparison 1 of Figures 1 and 6. This makes theshifting means self-locking independently ofY the fluid pressure,although the fluid pressure in the cylinder .70 also tends to maintainthe shifting mechanismY and the frame in the extreme position to whichthey are adjusted.

The discs 81 being constrained to roll back and forth in the slots S2 ofthe knee plate and being pinned to the pinions 78 which have bearingportions .79 rotatably mounted on the frame 1, aid in the support of thedog on the knee plate, and with the studs 63 and their slots (illvconstrain the dog to in and out movement on the knee plate.

From the foregoing-'it will be understood that the log engaging membersnot only may be powerfully forced into gripping engagement with the log,but may also be positively withdrawn therefrom. This reverse actuationof the log engaging members may be Y.carried outirrespective of theposition of the dog relative to the knee face; In other words, the logengaging members may be properly controlled and actuated with the dogshiftedout relative toi the knee face as shown Vin full lines inFigur-eand in dotted lines in Figure 2, and also when the dog is shifted inrelative to the knee face as shown in full lines iii-Figures and Il, andin either of these positions the log engaging members may be positivelymovedin either direction. These advantages are had inan organizationwhich utilizes lluid pressure/motors not only for actuatingthevlogengaging members, but also for shiftingA the dog in and out.Therfluid pressure motor which actuates the logI engaging members 'isiso ouraganize'd.with the intermediate chain and sprocket-s, and theintermediate ohain isso connected up with the log engaging members thatthe log engaging members areA moved'under the action ofa direct pullexerted in the line of movement of these members, thereby insuringsmooth and easymovement and avoiding tilting or binding. v Y i Theinvention claimed is:

1. A sawmill dog comprising a pair of log vengaging members mounted forsliding move- -ment toward and away from each other, a

fluid pressure motor, a flexiblel element, a guide member mounted on theframe and around which the -flexible element is trained 'and anactuating element lshifted by the fluid pressure motor and also engagedwith the flexible element. the opposite ends of the flexible elementbeing secured to the log holding members and 'moving in oppositedirections,V

for causiiig-the flexible element to positively move both logengagingmembers away from eachother when the fluid pressure motor is operatedfor such purposes.

, 2. A sawmill dog comprising' a frame, a pair of 'log engaging'`members slidably mounted on Vthe frame for movement toward and awayfrom eachother, a fluid pressure motor, a flexible element having itsends secured to the` log engaging members and eX- tended therefrom insubstantially the line of movement of said members, said flexibleelement having-a portion freely passing through one of. said lofi enraging members, and rotatable elements mounted on the frame and .on thefluid pressure motor and coacting with vthe flexible element whereby toexert aidirect straight line pull on the log engaging meinbers'and causethem to be drawn toward each other without binding upon appropriateoperation of the fluid pressure motor.

sawmill dog` comprising a frame, guides mount-ed on the frame, a pair oflog engaging members incliuiling slides slidably interengaged withthe-guides and also having teeth adapted for engaging the logl or thelike, a fluid pressure. motor mounted on the frame, apair of flexibleelements, each flexible' element being'connected to both log engagingme1nbers,

rotatable elements 130 mounted on the frame and around which-flexibleelements are trained and movable actuatiiigelements shifted by the fluidpressure motor andalso engaged with the flexible elements whereby thefluid pressure motor serves to positivelj,7 urge the log engagingmembers toward each other and also to positively retract both logengaging members.

4.-. A sawmill dog comprising a frame,

guide nieai'isfniounted on thel frame, a pair on the frame,fiexibleelements, and rotatableelementsl mounted on the frame and on the fluidpressure motor and around which the flexible element-s are trained,opposite ends ofthe flexible elements being connected to the log:engaging members kand moving in oppositev directions upon operation ofythe fluid pressure vmotor to positively move the log' engaging memberstoward each other when the fluid pressure motor is loperated A in onedirection and lto positively moveboth log engaging members away fromeach other when the fluid pressure motor is moved in an oppositedirection.

5. A sawmill dog comprising a frame, a

pair of log engaging members slidably mounted on the frame for movementtoward and away from each other, a fluid pressure motor including apiston having a piston rod fixedto the frame and a movable cylin-- derin which thepiston operates, controllable means for supplying andexhausting fluid pressure to the cylinder above and below the pistonwhereby the cylinder may be moved in either direction, a flexibleelement having its ends secured to the log engaging members and extendedvtherefrom in substantially the line of movement of said members, saidflexible element having a portion freely passing through one of the `logengaging members, a rotatable element mounted on the lower portion ofthe cylinder and around which .an intermediate portion of said flexibleelement is trained, a resiliently supported rotatable element mounted onthe frame and around which the flexible element is also passed, a secondflexible element having its ends connected to the log engaging membersand extending therefrom in directions opposite to those in which theends of the first mentioned flexible element extend from the logengaging members, a rotatable element mounted on the frame and aroundwhich a portion of the second flexible element passes, and a rotatableeleinent mounted onthe upper portion of. the cylinder and around whichanother portion of the second flexible element passes.

6. In a device of the character described, a knee, a sawmill dog havinga frame mounted on the knee for in and out movement, fluid pressuremotor mounted on thev frame, ro-

tata'ble'elements mounted on the .frame and4 actuated from thefluidpressuremotor, discs connected to said rotatable elements formovement therewith, said knee having a member provided with elongated`bearing openings for 'the discs, and means coacting withfthe discs andVwith said member for'cziusing the frame to move in and out relative tothe knee when the rotatable elements are rotated.

1. In a device of the character described, a knee, a sawmill dog havinga frame mounted on the knee for in and out movement, a fluidL pressuremotor mounted on the frame, rotatable elements mounted on the frame andactuated vfrom the fluid pressure motor, discs connected to saidVrotatable elements for move-4 ment therewith, said knee having a memberprovided with elongated bearing openings for the discs, and linkspivotally connected to saiddiscs and to said member for causing theframe to shift vrelative to the knee when-the. rotatable elements arerotated. Y

8. In `a device of the character described, a knee, a knee plate securedthereto, 'a sawmill dog having a frame, means for supporting the frameon the knee plate for in and out shifting movement, a'fluid pressuremotor including a cylinder fixed to the frame and a piston having apiston rod projecting from the opposite ends of the cylinder andprovided with racks, pinions' rotatably mounted on the frame and meshedwith the racks, discs fixed to the pinions, said knee plate havingelongated bear,-

ing lslots in which the discs are fitted, said" discs having flanges tolprevent their displacement from the bearing slots, and linksecceiitrically pivoted to the discs and also pivoted to the knee plate.1 Y

9. In afdevice of the character described, 'a knee, a knee plate securedthereto, a sawmill dog having a frame, means for supporting thefraiiie'on the knee plate'for in and` out shifting movement, a fluidpressure motorincluding a cylinder xed to the frame and a piston havinga piston rod projecting from the opposite ends of the cylinder andprovided with racks, pinionsrotatably 'mounted' on the frame and meshedwith the racks, discs fixed to the pinions, said knee plate havingelongated-bearing slots in which the discs vare fitted, fand linksecceiitrically pivoted to the discs and also pivotedto the knee plate.

10. In a device of the character described, a knee, a sawmilldoghavingav frame mounted j on the kneefor in and fout movement, a fluidbetween the pinions and the knee and operating to cause the dog 'to movein and out relative to the knee when the pinions kare rotated. n l1. A.sawmill dogcoinprising zi-frame, a

iio

iso

one of thelog engaging members, a rotatable element actuated by thefluid pressure motor and around which an intermediate portion of saidfiexible element is trained, a rotatable element mounted on the frameancla-round which the fiexible element is also passed, a second flexibleelement having` its ends coni nected to the log engaging members and eX-tendin'g therefrom in directions opposite to those in which the ends ofthe first mentioned flexible element extend from the log engagingmembers, a rotatable element mounted on the frame and around which aportion of the second flexible eleinentpasses, and a rotatek ableelement mounted on the fluid pressure motor and karound which anotherportion of' the second flexible element passes.

l2. A sawmill 'dog comprising a pair of log engaging members, a fluidpressure motor and a flexible element operated from the Huid pressuremotor and having oppositely moving portions connected tothe log engagingmembers for positively moving both log engaging members away from eachother upon appropriate actuation of theV fluid pressure motor.

k13. In a device of the character described, a. sawmill dog mount-ing,means supporting the sawmill dog mounting for in and out movement, afluid pressure motor carried by said mounting, rotatable elementsjournaled on said mounting and geared to `and actuated from said fluidpressure motor, and a link for each rotatable element, each link beingconstrained to oscillate about a fixed axis and being eccentricallyconnected toits rotatable l element.

14. In a device of the-character described, a knee` a sawmill dogmount-ing supported on the knee for in and out movement, a fluidpressure motor carried by said mounting, ro-

tatable elements journaled on the mounting and geared to and actuatedfrom the fluidA pressure motor, and links interposed betweentherotatable elements and the knee, each link having one endeccentrically pivoted to a rotatable element and having its other endconstrained to oscillate about anv axis fixed with respect to the knee,said links being positioned on dead center on either eXtreme position ofthe dog mounting.

l5. A sawmill dog'coinprising upper andY lower opposed log engagingmembers, guide mea-ns constraining said log engaging members tomovementtoward and away from each other in a vertical plane, areverselyoperable motor, means actuated from the motor when the saine is runin'one direction to positively urge the log engaging members toward eachother, a Vflexible clement, guide and actuating members coopci'able withthe flexible ele-l ment and deflecting the same to provide 0ppositelymoving portions, said oppositely moving portions being connected to bothlog engaging members to positively move both log engaging members awayfrom each other when said flexible element is positively actuated bysaid actuating member, and a driving connect-ion between said motor andsaid actuating member for so moving the actuating member as'to cause thesame to positively actuate the flexible element when said motor is runin an opposite direction.

16. le; dog for use on the knee of a sawmill carriage. and comprisingupper and lower opposed log engaging members, guide means constrainingsaid log engaging inembers to movement toward and away from eachother ina vertical plane, two flexible elements, two sets of guide and actuatingmembers,'said sets otguide and actuating l members engaging anddeflecting said flexible elements to provide oppositely moving portionsin each flexible element, one of said moving portions of each *elementbeing connected to oneV of said log engaging members and the other'ofsaid moving portions of each flexible element being connected to theotherv of said log engagingmembers, the connections of said oppositelymoving portions of said fle/:ril le elements with said log engagingmembers being'such that when one of said flexible elements is positivelyactuated by its actuating member it moves the dogs toward each other andwhen the other is so actuatedv it moves the dogs away from each other,arevers'ely operable motor, and driving connection between said motorand said actuating members whereby when said motor is run in onedirection the dogs are positively moved toward 'each other and when themotor is run in an opposite direction both dogs are positively pulledaway from each other.

In witness whereof, we hereto aiiix oursignatures.

ROSS LANGILL. STANLEY B. LANGILL.

